1. Field
Embodiments of the present invention relate to an electronic brake system, and, more particularly, to an electronic brake system capable of simplifying a structure and precisely controlling pressure.
2. Description of the Related Art
A brake system for the braking is necessarily mounted on a vehicle, and in recent years, a variety of systems for providing stronger and more stable braking have been proposed. For example, there are brake systems including an anti-lock brake system (ABS) for preventing a wheel from being slid while braking, a brake traction control system (BTCS) for preventing a driving wheel from being slipped when a vehicle is unintendedly or intendedly accelerated, an electronic stability control system (ESC) for stably maintaining a driving state of a vehicle by combining the ABS with a traction control to a control hydraulic pressure of a brake, and the like.
Such an electronic brake system includes multiple solenoid valves for controlling brake hydraulic pressure delivered to wheel cylinders mounted on wheels of a vehicle, a pair of a low-pressure accumulator and a high-pressure accumulator for temporarily storing oil discharged from the wheel cylinders, a motor and a pump for forced pumping of oil in the low-pressure accumulator, multiple check valves for preventing a backflow of oil, and an electronic control unit (ECU) for controlling the solenoid valves and driving of the motor, and these components are compactly installed in a hydraulic block made of aluminum. Also, a hydraulic pressure supply device is provided and used for delivering pressure to the wheel cylinders by receiving a driver's request for a braking force in the form of an electrical signal from a pedal displacement sensor that measures a displacement of a brake pedal when the driver steps on the brake pedal.
An electronic brake system provided with such a hydraulic pressure supply device is disclosed in U.S. Patent Application Publication No. 2012/0091787. According to the publication, the hydraulic pressure supply device is made to operate a motor depending on a pedal effort of a brake pedal to thereby generate a rotational force of the motor into a linear motion to pressurize a piston.
However, the electronic brake system with such a structure has a problem in that it is difficult to realize a rapid pressure generation and perform a precise control due to a simple structure of the hydraulic pressure supply device in which a pressurized piston must be returned again to the original position in order to be operated when regenerating a pressure or boosting a generated pressure.
Further, for controlling pressure flow according various control modes, the structure with multiple solenoid valves and a fluid path become complicated for sure, and a separate low-pressure accumulator as well as a motor and a pump for operation thereof need to be provided. Consequently, problems of increased weight and size of the system arise that cause degradations in mounting and space utilization as well as increased vibration and noise due to the operations of the motor and the pump.